Position-based limited-response mode operation in a vehicle communication system

ABSTRACT

A communication system for facilitating control over a function of a vehicle ( 102 ) comprises a base station ( 104 ) positioned in the vehicle ( 102 ) and a mobile communication unit ( 122 ). The base station ( 104 ) comprises a first transmitter for transmitting a signal to the mobile communication unit ( 122 ) and a first receiver for receiving a signal from the mobile communication unit ( 122 ). The base station ( 104 ) is configured to determine a location of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) and to cause the mobile communication unit ( 122 ) to operate in accordance with a limited-response mode when the location of the communication unit relative to the vehicle ( 102 ) remains substantially unchanged for a predetermined period of time.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/893,469, filed Nov. 23, 2015, which itself is a 35 U.S.C. §371 national stage application of PCT Application No. PCT/EP2014/061336, filed on Jun. 2, 2014, which claims priority from Great Britain Patent Application No. 1309747.2, filed on May 31, 2013, the contents of which are incorporated herein by reference in their entireties. The above-referenced PCT International Application was published in the English language as International Publication No. WO 2014/191572 A9 on Dec. 4, 2014.

TECHNICAL FIELD

The present invention relates to a vehicle communication system for facilitating control over vehicle functions. The present invention relates more particularly, but not exclusively, to systems and methods for facilitating control over vehicle functions based, at least in part, on position of a mobile communication unit. Aspects of the invention relate to a system, to a method and to a vehicle.

BACKGROUND OF THE INVENTION

In today's world, many vehicles are equipped with systems for facilitating remotely controlled vehicle functions such as passive entry and passive starting (i.e., PEPS) of a host vehicle. When a vehicle is equipped with a PEPS system, a user carries a mobile communication unit which can communicate with a base station located in the vehicle. To conserve use of energy stored in its internal battery, system components may remain in a low power state until an initiating trigger (for example, manipulation of a vehicle door handle) awakens one or more other system components. For example, upon sensing that a door handle has been manipulated, the base station may emit a relatively powerful Low Frequency (LF) electromagnetic field, causing a mobile communication unit that is sufficiently close to the base station to awaken. Once the mobile communication unit is awake, it may use Radio Frequency (RF) transmissions (i.e., communications) to dispatch a response signal, which may be validated by the base station. If the base station recognizes and approves the identity of the mobile communication unit, (i.e., the base station authenticates the mobile communication unit), the base station may facilitate the performance of a predefined vehicle function, such as actuating a door lock mechanism, causing the door to become unlocked.

Because the amount of energy required by the base station to generate a LF field is significant, many such systems employ a sleep mode and awaken only upon the occurrence of a trigger event. Unfortunately, the use of an initiating trigger necessitates that the sequence of authenticating the mobile communication unit be performed within an extremely short amount of time so as to avoid delays in response from the vehicle. Fast-release motors may be employed to perform the actuation functions such as unlocking a door.

Means may be provided for monitoring movements of the mobile communication unit such that, after a period of time in which the mobile communication unit has remained stationary and has not been otherwise activated, the mobile communication unit would be caused to enter the sleep mode. Unfortunately, when the mobile communication unit is in the vehicle, physical movements of the vehicle may be misinterpreted as movements of the mobile communication unit even though the mobile communication unit may be stationary with respect to the vehicle. Under those circumstances, the misinterpreted vehicle movements may prevent the mobile communication unit from entering the sleep mode whenever the vehicle is moving.

The present invention attempts to address or ameliorate at least some of the above problems associated with vehicle communication systems.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a communication system for facilitating control over a function of a vehicle comprising a base station positioned in the vehicle and a mobile communication unit. The base station comprises a first transmitter for transmitting a signal to the mobile communication unit and a first receiver for receiving a signal from the mobile communication unit. The base station is configured to determine a location of the mobile communication unit relative to the vehicle and to cause the mobile communication unit to operate in accordance with a limited-response mode when the location of the communication unit relative to the vehicle remains substantially unchanged for a predetermined period of time.

The base station may be configured to cause the mobile communication unit to operate in accordance with a limited-response mode when the location of the communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time. Accordingly, the invention provides for conserving energy stored in the battery of the mobile communication unit and unnecessary exercising of vehicle functions.

The base station may be configured to cause the mobile communication unit to operate in accordance with a limited-response mode when the location of the communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time. The base station may be configured to cause the mobile communication unit to operate in accordance with a limited-response mode when the location of the communication unit relative to the vehicle is within an authorization zone and the vehicle remains free from interruption for a predetermined period of time.

The mobile communication unit may comprise a motion sensor configured for detecting a movement of the mobile communication unit and for outputting a signal indicative of the movement. The signal may be sent to the base station. The base station may be configured to receive said signal indicative of a motion of the mobile communication unit and to cause the mobile communication unit to operate in accordance with a limited-response mode when the signal is indicative of the motion satisfying a predetermined limited-response criteria. The predetermined limited-response criteria may comprise freedom from movements exceeding a threshold level of at least one of a frequency, a distance/magnitude, a velocity or an acceleration magnitude.

The base station may be configured to receive the signals indicative of a motion of the mobile communication unit and to cause the mobile communication unit to resume operating in accordance with a high-response duty cycle when said signal is indicative of said motion satisfying a predetermined high-response criteria. The predetermined criteria may be based on a frequency of the motion. The predetermined criteria may also be based on a magnitude of the motion.

The base station may be configured to cause a sensitivity of the motion sensor to be adjusted. The base station may be configured to cause a sensitivity of the motion sensor to be adjusted when the location of the communication unit relative to the vehicle remains substantially unchanged for a predetermined period of time. Further, the base station may be configured to cause a sensitivity of the motion sensor to be adjusted when the location of the communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time.

The base station may be configured to cause a sensitivity of the motion sensor to be adjusted when the location of the communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time. The base station may also be configured to cause a sensitivity of the motion sensor to be adjusted when said signal is indicative of the motion satisfying a predetermined, limited-response criteria. The predetermined limited-response criteria may comprise freedom from movements exceeding a threshold acceleration magnitude. The predetermined criteria may be based on a frequency of said motion, on a magnitude of said motion, or on a duration of said motion.

The base station may be configured for determining a location of the mobile communication unit relative to the vehicle based on either a time of flight of communications between the mobile communication unit and three or more transceivers positioned in the vehicle or a time of flight of an ultra-wide band communication between the mobile communication unit and the three or more transceivers positioned in the vehicle.

The limited-response mode may comprise the mobile communication unit operating in accordance with a limited-response duty cycle. The limited-response duty cycle may comprise a transceiver of the mobile communications unit having active phases which are interrupted by periods of inactivity. In this way, the overall time for which the transceiver is active may be reduced compared to when the mobile communication unit operates in accordance with a high-response duty cycle. Alternatively, the limited response mode may comprise a sleep mode in which a transceiver of the mobile communication unit is inactive with no intermittent periods of activity.

In a further aspect, the present invention provides a method of facilitating control over a function of a vehicle comprising providing a base station positioned in the vehicle and a mobile communication unit, wherein the base station comprises a first transmitter and a first receiver. A signal is transmitted from the first transmitter to the mobile communication unit, and a signal is received from the mobile communication unit. A location of the mobile communication unit relative to the vehicle is determined, and, when the location of the mobile communication unit relative to the vehicle remains substantially unchanged for a predetermined period of time, the mobile communication unit is caused to operate in accordance with a limited-response mode. The step of causing the mobile communication unit to operate in accordance with a limited-response mode may be performed either when the location of the mobile communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time or when the location of the mobile communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time or alternatively when the location of the mobile communication unit relative to the vehicle is within an authorization zone and the vehicle remains free from interruption for a predetermined period of time.

The method may comprise detecting a movement of the mobile communication unit and outputting a signal indicative of the movement. The method may comprise receiving the signal indicative of a motion of the mobile communication unit such that causing the mobile communication unit to operate in accordance with a limited-response mode may be performed when the signal is indicative of the motion satisfying a predetermined limited-response criteria. Said predetermined limited-response criteria may comprise freedom from movements exceeding a threshold acceleration magnitude. The predetermined limited response criteria may be based on a frequency of said motion, on a magnitude of said motion, or on a duration of said motion.

The method may comprise receiving the signal indicative of a motion of the mobile communication unit and, when the signal is indicative of the motion satisfying a predetermined high-response criteria, causing the mobile communication unit to resume operating in accordance with a high-response duty cycle. The predetermined high-response criteria may be based on a frequency or magnitude of said motion. The detecting a movement of the mobile communication unit may be performed using a motion sensor such that a sensitivity of the motion sensor may be caused to be adjusted. A location of the mobile communication unit relative to the vehicle may be determined based on a time of flight of communications between the mobile communication unit and three or more transceivers positioned in the vehicle.

In another aspect, there is provided a vehicle having a communication system as described in the foregoing aspects which may be adapted to perform a method, as described in the preceding aspects.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. For example, features described in connection with one embodiment are applicable to all embodiments unless there is incompatibility of features.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which:

FIG. 1 shows a schematic representation of a vehicle communication system according to an embodiment of the present invention;

FIG. 2 shows the installation of the base station and transceivers of the vehicle communication system according to one embodiment of the present invention in a motor vehicle;

FIG. 3 shows an operating mode of the vehicle communication system according to one embodiment of the present invention;

FIG. 4 illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention;

FIG. 5 illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention; and

FIG. 6 illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 shows a vehicle communication system 100 in accordance with an embodiment of the present invention. The vehicle communication system 100 is configured to facilitate transfer of information among components of the vehicle communication system 100, which may further facilitate control over one or more functions of a vehicle 102. Exemplary functions that may be controlled include, but are not limited to, enhanced Passive Entry and Passive Start (ePEPS) keyless access, remote engine start, remote opening and closing of vehicle apertures, deployment and retraction of external mirrors or antennas, and/or activation and deactivation of lighting and signalling systems of the vehicle 102.

The vehicle communication system 100 will be described with reference to the vehicle 102 which has a front right door 142, a rear right door 144, a front left door 146 and a rear left door 148. The vehicle 102 also has a boot lid 150 (also known as a deck lid) which can be locked/unlocked by the vehicle communication system 100 but this is not described herein for the sake of brevity. The doors 142-148 each have a lock mechanism and an external handle; and the front doors 142, 146 each have a folding door mirror. The lock mechanisms each comprise a door lock switch to provide a locking signal to indicate the status of the respective lock mechanism.

The vehicle communication system 100 comprises a base station 104 to be installed in the vehicle 102 to provide a Remote Function Actuator (RFA) for the vehicle 102. The base station 104 comprises an electronic control unit 106 and a first rechargeable battery 108. The electronic control unit 106 comprises a memory storage device 107 that is in communication with one or more processor(s) 109. The processor(s) 109 can be configured to perform computational instructions stored in the memory storage device 107. The first rechargeable battery 108 provides a dedicated power supply for the base station 104 to enable its operation independently from a vehicle power system (not shown).

The base station 104 further comprises first, second and third ultra-wideband transceivers 110, 112, 114. The first transceiver 110 is provided proximal the electronic control unit 106. The second and third transceivers 112, 114 are positioned in the vehicle 102 remote from the electronic control unit 106 and connected via a dedicated local interconnect network (LIN) 116. The transceivers 110, 112, 114 each have an integrated antenna. As discussed more fully below, the vehicle communication system 100 may further comprise a fourth transceiver (not shown) which is also positioned in the vehicle 102 remote from the electronic control unit 106 and connected via the dedicated local interconnect network (LIN) 116.

The base station 104 is connected to the vehicle systems (denoted generally by the reference numeral 118) via a CAN bus 120. The base station 104 can thereby receive signals from the vehicle systems (e.g., locking signals from door lock switches); and can control operation of one or more vehicle systems (e.g., door lock mechanisms, closure systems for vehicle apertures such as windows, sun roof, ventilation systems, deck lid, engine start/ignition, vehicle lighting, entertainment systems, horn, heater, air conditioning, and the like). The CAN bus 120 can also be employed to convey instructions from the electronic control unit 106 to other systems (e.g., actuators, controls) of the vehicle 102, such as the engine control unit, to facilitate enabling and/or disabling of one or more vehicle systems (e.g., passive engine starting).

The vehicle communication system 100 further comprises a mobile communication unit 122 having a remote ultra-wideband transceiver 124 and a second rechargeable battery 126. The mobile communication unit 122 is portable to facilitate its being carried by the user. As described herein, the mobile communication unit 122 communicates with the base station 104 to facilitate control over vehicle functions, such as passive entry to the vehicle 102, and, under some circumstances, to provide information to a user in possession of the mobile communication unit 122.

The base station 104 further comprises a dock 128 for receiving the mobile communication unit 122. The dock 128 has a port 130 to enable communication between the base station 104 and the mobile communication unit 122. A charging pad 132 is also provided in the dock 128 to facilitate charging of the second rechargeable battery 126 when the mobile communication unit 122 is docked and thus mated with the charging pad 132. A bi-colour light emitting diode 134 is provided in the dock 128 to indicate the status of the mobile communication unit 122 (for example to indicate that the second rechargeable battery 126 is charging or is fully charged). The charging pad 132 is connected to a power supply unit (PSU) provided in the base station 104. An external charge port 136 for the base station 104 is provided for charging the first rechargeable battery 108.

The installation of the vehicle communication system 100 is illustrated in FIG. 2. The base station 104 and the first transceiver 110 are located at the rear of the vehicle 102 and the second and third transceivers 112, 114 are located in the upper part of the vehicle 102 (typically in the roof) on the right and left sides respectively of the vehicle 102. As illustrated by dashed lines in FIG. 2, the transceivers 110, 112, 114 communicate with the mobile communication unit 122. The distance from each of the first, second and third transceivers 110, 112, 114 to the remote transceiver 124 can be determined by measuring transmission and/or response time (for example, time of flight for a signal transmission) thereby allowing the position of the mobile communication unit 122 in relation to the vehicle 102 to be determined through triangulation. The use of ultra-wideband frequencies (typically greater than 3 GHz) allows the position of the mobile communication unit 122 to be tracked with a relatively high degree of accuracy.

In accordance with such an embodiment of the vehicle communication system 100, wherein the base station 104 comprises three transceivers 110, 112, 114 disposed at spaced apart locations within the vehicle 102, it is possible to use the transmission and/or response times for communications sent between the mobile communication unit 122 and each of the transceivers 110, 112, 114 to determine a position of the mobile communication unit 122 relative to the vehicle 102 along each of two axes. For example, with the base station 104 and the first transceiver 110 located toward the rear of the vehicle 102 and the second and third transceivers 112, 114 disposed within the roof (on respective left and right sides), the position of the mobile communication unit 122 relative to the vehicle 102 can readily be determined, i.e. as shown in the plan view of FIGS. 2 to 6.

However, with the second and third transceivers 112, 114 disposed in the vehicle roof, and therefore lying in the same horizontal plane, there may be situations in which it is not possible to readily determine the position of the mobile communication unit 122 along a direction normal to the plan views of FIGS. 2 to 6. Accordingly, in a further embodiment of the invention, the vehicle communication system 100 may comprise a fourth transceiver (not shown) which is disposed within the vehicle 102 at a location which is spaced apart in a vertical direction from both the plane of the vehicle roof and the horizontal plane in which the base station 104 lies. For example, the fourth transceiver (not shown) could be mounted in the vehicle dashboard on the vehicle center line. With this configuration, the height of the mobile communication unit 122 relative to the vehicle 102 can readily be determined.

Thus, a position of the mobile communication unit 122 relative to the vehicle 102 may be periodically or continuously determined and may be saved in the memory storage device 107 for subsequent retrieval and analyses by the processor 109. Such monitoring and storing and processing of position information may be useful for observing, tracking, and identifying certain rates, patterns, and/or characteristics of movement. For example, the vehicle communication system 100 may be configured to detect an approach of the mobile communication unit 122 toward an authorization zone 138 defined relatively to the vehicle 102, to detect a departure of the mobile communication unit 122 from the authorization zone 138, to detect a continuing presence of the mobile communication unit 122 within the authorization zone 138, and to recognize patterns involving combinations of approaches, departures, and prolonged presences relative to the authorization zone 138 of the vehicle 102.

The remote transceiver 124 of the mobile communication unit 122 transmits a polling signal which, when received by the first transceiver 110 of the base station 104, initiates communication between the base station 104 and the mobile communication unit 122. In one embodiment, upon receipt of the polling signal, the first transceiver 110 responds by transmitting a challenge signal. The challenge signal is received by the mobile communication unit 122 and prompts the mobile communication unit 122 to transmit a response signal. The electronic control unit 106 receives the response signal and attempts to determine whether it was sent by an authorized device (i.e., to validate or authenticate the mobile communication unit 122).

If the response signal is authenticated, the electronic control unit 106 continues to communicate with the mobile communication unit 122 and tracks its position in relation to the vehicle 102 and may store the position information in the memory storage device 107 for retrieval and processing by the processor 109 in accordance with pre-defined instructions. Moreover, provided the challenge/response sequence is completed successfully, the electronic control unit 106 will provide control over functions of the vehicle 102 subject to satisfaction of operating criteria. If the response signal is not authenticated, the electronic control unit 106 will not facilitate user control over vehicle functions, such as unlocking the doors of vehicle 102 or starting the engine of vehicle 102.

In one mode of operation, the polling signal is transmitted continually by the remote transceiver 124 so that communication with the base station 104 is initiated by the mobile communication unit 122. Accordingly, the vehicle communication system 100 can initiate a challenge/response cycle without the need for user interaction, such as actuating a door handle.

In another mode of operation, such as may be active upon first entry of the vehicle 102 into service, to conserve energy stored in the second rechargeable battery 126, the polling signal is transmitted for an operating period of thirty (30) days. The transmission of the polling signal is stopped if the mobile communication unit 122 does not establish communication with the base station 104 during the operating period. A button provided on the mobile communication unit 122 can be pressed to re-commence transmission of the polling signal after said operating period has expired.

In another embodiment, the polling signal is transmitted intermittently, rather than continuously. In accordance with this embodiment, the polling signal is repeated during the operating period with a time interval between transmission cycles (pulses), i.e. the polling signal is transmitted periodically during the operating period. The time interval between the transmission cycles can be modified in response to measured parameters. For example, the time interval between communications can be modified depending on the measured distance between the vehicle 102 and the mobile communication unit 122. For example, if the mobile communication unit 122 is close to the vehicle 102, the time interval can be reduced to one (1) second. Conversely, if the mobile communication unit 122 is relatively far away from the vehicle 102, the time interval can be increased to five (5) seconds.

The base station 104 and the mobile communication unit 122 can communicate with each other over a range of at least 20 metres. The authorization zone 138 is defined within the communication range. For example, the authorization zone 138 may be defined as having a radius of 2 metres around the vehicle 102. When the electronic control unit 106 determines that the mobile communication unit 122 is inside the authorization zone 138, the base station 104 may facilitate automatic unlocking of one or more of the vehicle's doors 142-148. Conversely, when the electronic control unit 106 determines that the mobile communication unit 122 is outside the authorization zone 138, the base station 104 may cause the automatic locking of the vehicle's doors 142-148.

As discussed above, a vehicle communication system 100 comprising three or fewer transceivers may be able to determine a position of the mobile communication unit 122 relative to the vehicle 102 along only two axes. Accordingly, the authorization zone 138 may be defined in terms of only those two axes. A vehicle communication system 100 comprising four or more transceivers, however, may be able to determine a position of the mobile communication unit 122 relative to the vehicle 102 along any combination of three (optionally orthogonal) axes. Accordingly, the location of the authorization zone 138 may be defined in terms positions along each of the three axes, such that the authorization zone 138 (and thus the set of locations that are outside the authorization zone 138) may be defined in terms of three-dimensional space relative to the vehicle 102.

Being able to accurately determine the position of the mobile communication unit 122 in a three-dimension space around the vehicle 102 may be particularly useful in certain situations, for example when the vehicle 102 is parked in a multi-level or multi-story car park or adjacent to a multi-story building. In such situations it is possible that the driver, having exited the vehicle 102 may move to another level of the car park or building above or below the vehicle 102, but may still be sufficiently close to the vehicle 102 to be within the authorization zone 138, resulting in one or more of the vehicle doors being unlocked.

Accordingly, if it is determined that the mobile communication unit 122 is disposed sufficiently above or below the vehicle 102, such as in the example of the multi-level car park, the electronic control unit 106 may not unlock the vehicle doors even when the mobile communication unit 122 would otherwise be judged to be within the authorization zone 138.

The electronic control unit 106 may be configured to operate the vehicle communication system 100 according to a number of operating modes. In a number of scenarios, the mobile communication unit 122 is carried on the person of the user and therefore follows the movements of the user. In the accompanying figures, movement paths of the user, and therefore, the mobile communication unit 122, are illustrated by a set of footprints 140. The process performed by the base station 104 for authenticating the mobile communication unit 122 is the same as described above and is common to each of the operating modes.

In particular, the remote transceiver 124 transmits a polling signal which initiates an authentication cycle with the first transceiver 110. The base station 104 transmits a challenge signal which triggers transmission of a response signal from the mobile communication unit 122. The electronic control unit 106 validates the response signal and, if successful, the base station 104 tracks the range and position of the authenticated mobile communication unit 122. If the authentication cycle is not successfully completed, for example due to an incorrect response signal being sent from the mobile communication unit 122, the doors 142-148 will not be unlocked, and the vehicle 102 will not respond to the mobile communication unit 122.

The electronic control unit 106 may be configured to operate the vehicle communication system 100 according to a first operating mode as illustrated in FIG. 3. In this operating mode, the vehicle communication system 100 operates to unlock the doors 142-148 on the side of the vehicle 102 on which the user approaches with the mobile communication unit 122. Having authenticated the mobile communication unit 122, the base station 104 tracks the range and position of the mobile communication unit 122. In the illustrated example, the electronic control unit 106 determines that the mobile communication unit 122 is on the right hand side of the vehicle 102. Once the base station 104 determines that the mobile communication unit 122 is within the authorization zone 138, the electronic control unit 106 automatically generates a door unlock signal to unlock both doors 142, 144 on the right hand side of the vehicle 102. The door unlock signal is transmitted via the CAN bus 120, and the front right door 142 and the rear right door 144 are both unlocked when the mobile communication unit 122 enters the authorization zone 138. As the doors 142, 144 are unlocked before the user operates the respective door handle, in normal operating conditions it is envisaged that there would be no perceptible delay when the user operates the door handle.

In this mode, when the user operates the door handle on either the front right door 142 or the rear right door 144, either a single-point entry (SPE) or a multiple-point entry (MPE) can be initiated. In single-point entry mode, when the driver's door is the only opened door and the key fob is taken into the vehicle, the rear door on the approached side will be re-locked. For the avoidance of doubt, the driver's door does not have to be closed to effect the locking of the rear door. If ANY door other than driver's door is opened, then all doors will be unlocked and remain so. The action of locking the rear door on the driver's side is caused by the key fob being detected inside the vehicle and thus no longer seen in the authorisation zone on the outside of the vehicle. In a multiple-point entry, the electronic control unit 106 generates control signals to unlock all of the other doors in the vehicle 102 when the door handle of either the front right door 142 or the rear right door 144 is operated. It will be appreciated that the front left door 146 and the rear left door 148 will be unlocked if base station 104 determines that the mobile communication unit 122 enters the authorization zone 138 on the left hand side of the vehicle 102. Only when the door handle of one of the unlocked doors 142-148 is operated is an indication provided that the doors have been unlocked, for example by flashing the side repeaters and/or extending the door mirrors. If none of the door handles are operated, however, no indication is provided that one or more of the doors 142-148 have been unlocked.

The electronic control unit 106 may be configured to operate the vehicle communication system 100 according to a second operating mode as illustrated in FIG. 4 to accommodate a walk-past scenario. In this walk-past scenario, the user enters and exits the authorization zone 138 but does not operate a door handle. As in the first mode described above, the base station 104 authenticates the mobile communication unit 122 as it approaches the vehicle 102. In this case, the base station 104 tracks the position of the mobile communication unit 122 and determines that the user is approaching from the rear of the vehicle 102 on the right hand side. As described above in regard to the first mode of operation, when the vehicle communication system 100 detects that the mobile communication unit 122 has entered the authorization zone 138, as it has in this walk-past scenario, a door unlock signal is transmitted to unlock the front right door 142 and the rear right door 144.

In this scenario, however, the user does not operate the door handle on either of the doors 142, 144 and, instead, walks past the vehicle 102. Since the vehicle communication system 100 is tracking the position of the mobile communication unit 122, the vehicle communication system 100 is able to determine when the mobile communication unit 122 leaves the authorization zone 138. Accordingly, upon the departure of the mobile communication unit 122 from the authorization zone 138, and lacking the receipt of any indication that a door handle has been operated, the base station 104 transmits a door lock signal to lock the front right door 142 and the rear right hand door 144 or otherwise facilitates the re-locking of those doors. In one embodiment, the vehicle 102 does not provide a visual indication when the doors 142, 144 are unlocked or subsequently locked.

The electronic control unit 106 may be configured to operate the vehicle communication system 100 according to a third operating mode as illustrated in FIG. 5 to facilitate the automatic locking of the doors 142-148 when the user walks away from the vehicle 102. In this scenario, the user exits the vehicle 102 carrying the mobile communication unit 122 and closes the vehicle doors 142-148. In the illustrated example, the user exits the vehicle 102 through the front right door 142 and then closes it. The user then walks away from the vehicle 102 carrying the mobile communication unit 122. As the mobile communication unit 122 is carried away from the vehicle 102, the vehicle communication system 100 tracks the location of the mobile communication unit 122 and compares that location to the definition of the authorization zone 138. If and when the vehicle communication system 100 determines that the mobile communication unit 122 has left the authorization zone 138, the vehicle communication system 100 transmits a door lock signal to lock the doors 142-148. The vehicle 102 is thereby secured automatically without the user activating the mobile communication unit 122 or taking any action other than walking away from the vehicle 102. A security protocol to comply with industry standards, for example those specified by Thatcham®, would typically be undertaken for the automatic locking of the doors 142-148. Under normal operating conditions, the automatic locking of the vehicle 102 does not double-lock the vehicle 102. Rather, the vehicle 102 would only be double-locked if the user specifically selected this locking mode, for example via a control panel in the vehicle 102.

The electronic control unit 106 may be further configured to operate the vehicle communication system 100 according to a fourth operating mode as illustrated in FIG. 6 to accommodate a mis-lock scenario. This mode is similar to the third operating mode described above insofar as the user exits the vehicle 102 through the front right door 142 and closes the door 142 before walking away from the vehicle 102. In connection with this fourth operating mode, the vehicle communication system 100 again determines if and when the mobile communication unit 122 has departed the authorization zone 138. As illustrated in FIG. 6, however, the rear left door 148 is ajar, and the electronic control unit 106 determines that the door 148 cannot be locked (a so-called mis-lock).

To avoid the user leaving the vehicle 102 in an unsecure state (as may otherwise occur if the operator had not noticed that the rear left door 148 was ajar) the electronic control unit 106 transmits an alert signal to the CAN bus 120 and a notification is provided to the user. For example, the CAN bus 120 may illuminate the side repeaters and/or provide an audible warning to notify the user that the doors 142-148 have not all been locked. When the rear left door 148 is closed, the vehicle communication system 100 will lock the door 148 to secure the vehicle 102.

In conjunction with the above-described modes of operation, the electronic control unit 106 may be configured to operate the vehicle communication system 100 according to a fifth operating mode, accommodating a picnic scenario. In order to conserve energy stored in the second rechargeable battery 126 of the mobile communication unit 122, to avoid unintended and unnecessary actuation of vehicle systems, and to conserve energy in the components of the system, it may be desirable, in certain situations, for one or more components of the vehicle communication system 100, such as the mobile communication unit 122, to operate in a modified, energy-conserving manner. For example, when the mobile communication unit 122 has remained substantially stationary relative to the vehicle 102 for greater than a predetermined period of time, yet remains in a location within the authorization zone 138, it may be determined that the likelihood of an immediate and urgent need for two-way communication involving the mobile communication unit 122 may be relatively low. Accordingly, it may be desirable for the base station 104 to be able to determine whether certain criteria for a picnic scenario have been met and, if so, to instruct the mobile communication unit 122 to enter a reduced-sensitivity, energy-conserving picnic mode.

In support of the ability to discriminate between the picnic scenario (wherein a slower response time may be acceptable) and other modes (in which a relatively fast response time is deemed necessary), the base station 104 is configured to recognize attributes of a picnic scenario. These attributes may be characterized based on experience. For example, it is anticipated that a picnic scenario is appropriately identified when: (1) the mobile communication unit 122 remains present within the authorization zone 138, for a time period (i.e., a residence period) that exceeds a predetermined threshold length of time; and (2) during the residence period, the vehicle 102 remains free from interruption (i.e., a user does not attempt to gain access to the vehicle 102 and issues no commands to the vehicle 102—either passively or actively). An active command would include pressing a button to initiate a remote start or to open or close a window or the sunroof. A passive command would include entering or exiting the authorization zone 138. Upon recognition of a picnic scenario, the base station 104 is configured to command the mobile communication unit 122 to enter a limited-response mode. In other words, the mobile communication unit 122 enters a sleep mode.

As described above, the mobile communication unit 122 may contain an internal motion sensor 152 configured for detecting movements of the mobile communication unit 122 and sending signals indicative of those movements. The mobile communication unit 122 receives signals from the motion sensor 152 and, based on the frequency and/or magnitude of the accelerations, the mobile communication unit 122 decides whether and when to enter or exit a sleep mode. For example, following a period of time in which no accelerations of sufficient magnitude are detected (i.e., a sensed acceleration magnitude fails to exceed a predetermined threshold) or a period of time in which an insufficient number of acceleration events are detected within an amount of time (i.e., an acceleration frequency fails to exceed a predetermined threshold), then the mobile communication unit 122 may decide to enter a sleep mode.

Alternatively, the mobile communication unit 122 may transmit a signal to the base station 104, and the base station 104 may decide whether and when to instruct the mobile communication unit 122 to enter the sleep mode based on the transmitted acceleration magnitude or acceleration frequency signal. Conversely, when an acceleration of sufficient magnitude is detected (i.e., a sensed acceleration magnitude exceeds a predetermined threshold) or a sufficient number of acceleration events are detected within an amount of time (i.e., an acceleration frequency exceeds a predetermined threshold), then the mobile communication unit 122 may decide to exit the sleep mode. Alternatively, the mobile communication unit 122 may transmit a signal to the base station 104, and the base station 104 may decide whether and when to instruct the mobile communication unit 122 to exit the sleep mode based on the transmitted acceleration magnitude or acceleration frequency signal.

Under normal operating conditions, the mobile communication unit 122 is configured to rely upon the motion sensor 152 so that when no movement is detected for a predetermined period of time, the mobile communication unit 122 enters a sleep mode. Unfortunately, the mobile communication unit 122 may unnecessarily remain awake if it is located in close proximity to the vehicle 102, and undergoes incidental movements, such as might be experienced if the mobile communication unit 122 were in the pocket of a user relaxing in the vicinity of the vehicle 102 (e.g., enjoying a picnic, watching a youth soccer match). Accordingly, a limited-response mode may also involve de-sensitizing the internal motion sensor 152 of the mobile communication unit 122 in addition to suspending the transmission of ID pulses.

As described above, the base station 104 may be configured to recognize a picnic scenario in which the mobile communication unit 122 remains within the authorization zone 138 for an extended period of time and the motion sensor 152 signals indicate that the mobile communication unit 122 is actively moving, yet the user initiates no commands—either actively of passively—upon the vehicle 102. Upon recognition of a picnic scenario, the base station 104 is configured to command the mobile communication unit 122 to enter a limited-response mode. Where the mobile communication unit 122 is equipped with a motion sensor 152, and the mobile communication unit 122 is configured for awakening in response to suitable signals received from the motion sensor 152, activation of a suitable limited-response mode for such a mobile communication unit 122 may involve de-sensitizing of the internal motion sensor 152 of the mobile communication unit 122 in addition to suspension of transmission of ID pulses.

Desensitizing the internal motion sensor 152 of the mobile communication unit 122 may involve increasing the predetermined threshold such that only a fairly strident movement would wake up the mobile communication unit 122. This will conserve energy within the second rechargeable battery 126 of the mobile communication unit 122, but may still permit relatively large movements to reawaken the mobile communication unit 122. Upon a subsequent initiation of a command upon the vehicle 102, the base station 104 may instruct the mobile communication unit 122 to return to a normal level of sensitivity of the motion sensor 152.

Characteristics of the acceleration signal that may be evaluated for determining whether criteria associated with the picnic scenario are met (or are no longer met) may include magnitude, frequency, duration and the integral (i.e., a combination of the magnitude and duration) of the acceleration signal. For example, in one embodiment, the picnic scenario is indicated if the vehicle 102 perceives a sufficient number of wake ups with in a predetermined period of time. A reduced sensitivity of the motion sensor 152 signal may accordingly be configured to distinguish between a user's standing up versus merely shifting in his or her seat. Such a distinction would be relevant if standing up were deemed likely to precede an attempt to gain entry to the vehicle 102, whereas shuffling in the seat would not. In one embodiment, a picnic scenario is indicated by a suitable combination of motion sensor 152 parameters and how far the mobile transmitter-receiver may have moved within a specific period of time.

By recognizing the picnic scenario and taking appropriate remedial action, such as by desensitizing the motion sensor 152 and/or commanding the mobile communication unit 122 to enter a sleep mode or another form of power-saving mode, the system may avoid the negative consequences of unnecessarily activating functions of the vehicle 102 (e.g., over-exercising of the door locks) and unnecessarily depleting power in the components of the vehicle communication system 100.

In one embodiment, it is the base station 104 that determines whether a picnic scenario is invoked and accordingly dispatches a command to modify operation of the mobile communication unit 122. Upon receipt of such a command from the base station 104, the transceiver 124 of the mobile communication unit 122 may be caused to perform according to a modified, limited-response duty cycle. It should be appreciated that, while the vehicle communication system 100 is operating in a mode that requires relatively immediate response from the mobile communication unit 122, the transceiver 124 of the mobile communication unit 122 operates according to a high-response duty cycle such that the transceiver 124 remains substantially active at all times, with relatively little or no periods of inactivity. Accordingly, relatively little time lag exists between a transmission of a command signal from the first transceiver 110 and a transmission of a response from the mobile communication unit 122.

When the mobile communication unit 122 performs according to the modified, limited-response, duty cycle, however, the transceiver 124 of the mobile communication unit 122 may remain substantially inactive for the majority of each cycle, with relatively little time of activity within each cycle. Therefore, a relatively greater time lag exists between transmission of a command signal from the first transceiver 110 and the transmission of a response from the mobile communication unit 122.

Accordingly, a high-response duty cycle comprises an active phase that occurs without substantial interruption by an inactive phase. A limited-response duty cycle comprises active phases that are interrupted by periods on inactivity. In one such embodiment, a period of inactivity may extend for approximately two seconds, during which time the transceiver 124 is in an inactive state and therefore unable to receive a transmission, such as a command signal transmitted by the base station 104. In each active phase occurring between the periods of inactivity, the transceiver 124 of the mobile communication unit 122 is activated for a few microseconds (e.g., between approximately one microsecond and approximately ten microseconds, for approximately three microseconds). During these intervening active periods, the transceiver 124 is capable of receiving communications, including command, polling or challenge signals or other information transmitted by the base station 104. During extended time periods of inactive presence within the authorization zone 138, the mobile communication unit 122 performs this modified, limited-response, duty cycle, continuously alternating between the longer periods of deactivation and the relatively brief periods of activation. Thus, in accordance with this modified duty cycle, energy consumption by the mobile communication unit 122 may be substantially reduced.

In the event that it becomes necessary or useful to resume two-way communications between the base station 104 and the mobile communication unit 122, the base station 104 transmits a continuous wake-up transmission pulse lasting for at least as long as the length of each period of deactivation. Accordingly, as soon as the mobile communication unit 122 enters an active phase in its duty cycle, the mobile communication unit 122 encounters the wake-up transmission pulse. Upon receiving the wake-up transmission pulse, the mobile transmitter-receiver would take the appropriate action depending on what the base station 104 commands the mobile communication unit 122 to do.

A number of scenarios may arise wherein it may be desirable for the base station 104 to resume communications with the mobile communication unit 122 during the picnic mode. For example, whenever a door is opened and closed, it may be necessary to perform a search for the presence of a mobile communication unit 122 within the passenger compartment of the vehicle 102. If there is no mobile communication unit 122 present, the base station 104 may alert the driver and/or disable certain features and functions of the vehicle, in particular to disable the engine or immobilise the vehicle. To facilitate the search, a wake-up command is issued by the base station 104 whenever a door is opened. Thus, the vehicle communication system 100 provides an energy-saving picnic mode without compromising relatively continuous communication between the base station 104 and the mobile communication unit 122.

The vehicle communication system 100 can optionally also provide keyless engine starting for the vehicle 102. By using the ranging data from the transceivers 110, 112, 114, the electronic control unit 106 can determine when the mobile communication unit 122 is inside the vehicle 102. A control signal can be transmitted to the engine control unit, via the CAN bus 120, to permit keyless engine starting when a Start button is pressed.

The vehicle communication system 100 according to the present invention can be further refined. In particular, the electronic control unit 106 can be configured to transmit a status signal to the mobile communication unit 122. For example, if the base station 104 detects a mis-lock scenario, the status signal may instruct the mobile communication unit 122 to generate a first user alert. Equally, the status signal may instruct the mobile communication unit 122 to generate a second user alert (which is different from the first user alert) when the vehicle 102 has been locked. The first and/or the second user alert could be provided instead of, or in addition to, any notification provided by the vehicle 102. The mobile communication unit 122 could comprise an audio, optical or haptic output for indicating the vehicle status. For example, the mobile communication unit 122 could comprise one or more of the following: LED(s), a text screen or a vibrating mechanism.

The mobile communication unit 122 is also provided with one or more buttons to allow a user to trigger locking/unlocking of the vehicle doors from outside of the authorization zone 138.

The ultra-wideband (UWB) transceivers 110, 112, 114, 124 described herein are compliant with IEEE802.15.4a protocol.

The vehicle communication system 100 can monitor time of flight (ToF) communications between the base station 104 and the mobile communication unit 122 to provide improved security, for example to protect against a relay-station security attack.

A door unlock override switch can be provided to unlock the doors 142-148 in the event of an emergency.

The skilled person will understand that various changes and modifications can be made to the vehicle communication system 100 described herein without departing from the spirit and scope of the present invention. For example, a welcome lights function could be supported by illuminating an interior and/or exterior vehicle light when the mobile communication unit 122 enters the authorization zone 138.

Although the vehicle communication system 100 has been described with reference to the mobile communication unit 122 transmitting the polling signal, the system could also operate if the base station 104 transmitted the polling signal. For example, the first transceiver 110 of the base station 104 may transmit a polling signal which, when, received by the remote transceiver 124, initiates communication between the mobile communication unit 122 and the base station 104. In one embodiment, upon receipt of the polling signal, the mobile communication unit responds by transmitting a response signal. The response signal is received by the first transceiver 110 and the electronic control unit 106 validates the response signal.

The mobile communication unit 122 includes a motion sensor 152, such as a gyroscope or an accelerometer, to detect movements of the mobile communication unit 122. Signals based on the detected movements may then be transmitted to the base station 104 for use in deciding whether, when and how to facilitate control over vehicle functions. For example, if the base station 104 determines that the mobile communication unit 122 has been stationary for a predetermined period of time, the base station 104 may cause the mobile communication unit 122 to be disabled or to enter a sleep mode. In addition, the base station 104 could transmit a disable signal to deactivate the transceivers 110, 112, 114, 124. Alternatively, the transceivers 110, 112, 114, 124 could be disabled automatically if they do not receive an authorization signal for a predetermined period of time. The mobile communication unit 122 could be awakened by an activation signal from the motion sensor 152 when it detects movement. Alternatively, when the vehicle communication system is operating according to the aforementioned fifth operating mode, wherein the mobile communication unit 122 remains within the authorization zone 138 for an extended period of time and the motion sensor 152 signals indicate that the mobile communication unit 122 is actively moving, yet the user initiates no commands—either actively of passively—upon the vehicle 102, then the base station 104 shall instruct the mobile communication unit 122 to enter the limited-response picnic mode.

Moreover, it will be appreciated that it is not necessary for a vehicle communication system 100 according to the present invention to provide all of the operating modes described herein. Rather, one or more of the operating modes could be embodied in a communication system in accordance with the present invention.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the present invention. Further aspects of the present invention will be described with reference to the following numbered paragraphs.

1. A communication system for facilitating control over a function of a vehicle (102), the communication system comprising:

-   -   a base station (104) positioned in the vehicle (102); and     -   a mobile communication unit (122);     -   the base station (104) comprising a first transmitter for         transmitting a signal to the mobile communication unit and a         first receiver for receiving a signal from the mobile         communication unit (122);     -   the base station (104) being configured to determine a location         of the mobile communication unit (122) relative to the vehicle         (102) and to cause the mobile communication unit (122) to         operate in accordance with a limited-response duty cycle when         the location of the mobile communication unit (122) relative to         the vehicle (102) remains substantially unchanged for a         predetermined period of time.

2. A communication system as described in paragraph 1, wherein the base station (104) is configured to cause the mobile communication unit (122) to operate in accordance with a limited-response duty cycle when the location of the mobile communication unit (122) relative to the vehicle (102) remains within an authorization zone (138) for a predetermined period of time.

3. A communication system as described in paragraph 1, wherein the base station (104) is configured to cause the mobile communication unit (122) to operate in accordance with a limited-response duty cycle when the location of the mobile communication unit (122) relative to the vehicle (102) is within an authorization zone (138) and remains relatively unchanged for a predetermined period of time.

4. A communication system as described in paragraph 1, wherein the base station (104) is configured to cause the mobile communication unit (122) to operate in accordance with a limited-response duty cycle when the location of the mobile communication unit (122) relative to the vehicle (102) is within an authorization zone (138) and the vehicle (102) remains free from interruption for a predetermined period of time.

5. A communication system as described in paragraph 1, wherein the mobile communication unit (122) comprises a motion sensor (152) configured for detecting a movement of the mobile communication unit (122) and for sending a signal indicative of the movement.

6. A communication system as described in paragraph 5, wherein the base station (104) is configured to receive said signal indicative of a motion of the mobile communication unit (122) and to cause the mobile communication unit (122) to operate in accordance with a limited-response duty cycle when said signal is indicative of said motion satisfying a predetermined limited-response criteria.

7. A communication system as described in paragraph 6, wherein said predetermined limited-response criteria comprises freedom from movements exceeding a threshold level of at least one of a frequency, a distance/magnitude, a velocity, or an acceleration threshold magnitude?

8. A communication system as described in paragraph 5, wherein the base station (104) is configured to receive said signal is indicative of a motion of the mobile communication unit (122) and to cause the mobile communication unit (122) to resume operating in accordance with a high-response duty cycle when said signal is indicative of said motion satisfying a predetermined high-response criteria.

9. A communication system as described in paragraph 8, wherein the predetermined high-response criteria is based on a frequency of said motion.

10. A communication system as described in paragraph 8, wherein the predetermined high-response criteria is based on a magnitude of said motion.

11. A communication system as described in paragraph 5, wherein the base station (104) is configured to cause a sensitivity of the motion sensor (152) to be adjusted.

12. A communication system as described in paragraph 11, wherein the base station (104) is configured to cause a sensitivity of the motion sensor (152) to be adjusted when the location of the mobile communication unit (122) relative to the vehicle (102) remains substantially unchanged for a predetermined period of time.

13. A communication system as described in paragraph 11, wherein the base station (104) is configured to cause a sensitivity of the motion sensor (152) to be adjusted when the location of the mobile communication unit (122) relative to the vehicle (102) remains within an authorization zone (138) for a predetermined period of time.

14. A communication system as described in paragraph 11, wherein the base station (104) is configured to cause a sensitivity of the motion sensor (152) to be adjusted when the location of the mobile communication unit (122) relative to the vehicle (102) is within an authorization zone (138) and remains relatively unchanged for a predetermined period of time.

15. A communication system as described in paragraph 11, wherein the base station (104) is configured to cause a sensitivity of the motion sensor (152) to be adjusted when said signal is indicative of said movement satisfying a predetermined limited-response criteria.

16. A communication system as described in paragraph 15, wherein said predetermined limited-response criteria comprises freedom from movements exceeding a threshold acceleration magnitude.

17. A communication system as described in paragraph 15, wherein the predetermined limited-response criteria is based on a frequency of said movement.

18. A communication system as described in paragraph 15, wherein the predetermined limited-response criteria is based on a magnitude of said movement.

19. A communication system as described in paragraph 15, wherein the predetermined limited-response criteria is based on a duration of said movement.

20. A communication system as described in paragraph 1, wherein the base station (104) is configured for determining a location of the mobile communication unit (122) relative to the vehicle (102) based on a time of flight of communications between the mobile communication unit (122) and three or more transceivers (110) positioned in the vehicle (102).

21. A communication system as described in paragraph 20, wherein the base station (104) is configured for determining a location of the mobile communication unit (122) relative to the vehicle (102) based on a time of flight of an ultra-wide band communication between the mobile communication unit (122) and the three or more transceivers (110) positioned in the vehicle (102).

22. A method of facilitating control over a function of a vehicle (102) comprising:

-   -   providing a base station (104) positioned in the vehicle (102)         and a mobile communication unit (122), the base station (104)         comprising a first transmitter and a first receiver;     -   transmitting a signal from the first transmitter to the mobile         communication unit (122);         receiving a signal from the mobile communication unit (122); and     -   determining a location of the mobile communication unit (122)         relative to the vehicle (102); and     -   when the location of the mobile communication unit (122)         relative to the vehicle (102) remains substantially unchanged         for a predetermined period of time, causing the mobile         communication unit (122) to operate in accordance with a         limited-response duty cycle.

23. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, wherein said causing the mobile communication unit (122) to operate in accordance with a limited-response duty cycle is performed when the location of the mobile communication unit (122) relative to the vehicle (102) remains within an authorization zone (138) for a predetermined period of time.

24. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, wherein said causing the mobile communication unit (122) to operate in accordance with a limited-response duty cycle is performed when the location of the mobile communication unit (122) relative to the vehicle (102) is within an authorization zone (138) and remains relatively unchanged for a predetermined period of time.

25. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, wherein said causing the mobile communication unit (122) to operate in accordance with a limited-response duty cycle is performed when the location of the mobile communication unit (122) relative to the vehicle (102) is within an authorization zone (138) and the vehicle (102) remains free from interruption for a predetermined period of time.

26. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, further comprising detecting a movement of the mobile communication unit (122) and sending a signal indicative of the movement.

27. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22:

-   -   further comprising receiving said signal indicative of a motion         of the mobile communication unit (122);     -   wherein said causing the mobile communication unit (122) to         operate in accordance with a limited-response duty cycle is         performed when said signal is indicative of said motion         satisfying a predetermined limited-response criteria.

28. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, further comprising:

-   -   receiving said signal indicative of a motion of the mobile         communication unit (122); and     -   when said signal is indicative of said motion satisfying a         predetermined high-response criteria, causing the mobile         communication unit (122) to resume operating in accordance with         a high-response duty cycle.

29. A method of facilitating control over a function of a vehicle (102) as described in paragraph 26:

-   -   wherein said detecting a movement of the mobile communication         unit (122) is performed using a motion sensor (152);     -   further comprising causing a sensitivity of the motion sensor         (152) to be adjusted.

30. A method of facilitating control over a function of a vehicle (102) as described in paragraph 22, wherein said determining a location of the mobile communication unit (122) relative to the vehicle (102) is performed based on a time of flight of communications between the mobile communication unit (122) and three or more transceivers (110) positioned in the vehicle (102).

31. A vehicle (102) having a communication system, or being adapted to perform a method as described in paragraph 1 or 22. 

1. A communication system for facilitating control over a function of a vehicle, the communication system comprising: a base station; and a mobile communication unit comprising a motion sensor configured to detect movement of the mobile communication unit and to output a signal indicative of the movement; wherein the base station comprises a first transmitter configured to transmit a signal to the mobile communication unit and a first receiver configured to receive a signal from the mobile communication unit; wherein the base station is configured to determine a location of the mobile communication unit relative to the vehicle and to cause the mobile communication unit to operate in accordance with a limited-response mode when the location of the mobile communication unit relative to the vehicle remains substantially unchanged for a predetermined period of time.
 2. The communication system of claim 1, wherein the base station is configured to cause the mobile communication unit to operate in accordance with the limited-response mode when at least one of: (i) the location of the mobile communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time; (ii) the location of the mobile communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time; and (iii) the location of the mobile communication unit relative to the vehicle is within an authorization zone and the vehicle remains free from interruption for a predetermined period of time.
 3. The communication system of claim 1, wherein the base station is configured to receive said signal indicative of the movement of the mobile communication unit and to cause the mobile communication unit to operate in accordance with the limited-response mode when said signal is indicative of said motion satisfying a predetermined limited-response criteria.
 4. The communication system of claim 3, wherein said predetermined limited-response criteria comprises freedom from movements exceeding a threshold level of at least one of a frequency, a distance/magnitude, a velocity, or an acceleration threshold magnitude.
 5. The communication system of claim 1, wherein the base station is configured to receive said signal indicative of the movement of the mobile communication unit and to cause the mobile communication unit to resume operating in accordance with a high-response duty cycle when said signal is indicative of the movement satisfying a predetermined high-response criteria.
 6. The communication system of claim 5, wherein the predetermined high-response criteria is based on a frequency of said movement or on a magnitude of said movement.
 7. The communication system of claim 1, wherein the base station is configured to cause a sensitivity of the motion sensor to be adjusted when at least one of: (i) the location of the mobile communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time; and (ii) the location of the mobile communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time.
 8. The communication system of claim 1, wherein the base station is configured to cause the sensitivity of the motion sensor to be adjusted when said signal is indicative of said movement satisfying a predetermined limited-response criteria.
 9. The communication system of claim 8, wherein said predetermined limited-response criteria comprises freedom from movements exceeding a threshold acceleration magnitude and/or is based on one or more of a frequency of said movement, a magnitude of said movement, and/or a duration of said movement.
 10. The communication system of claim 1, wherein the base station is configured to determine the location of the mobile communication unit relative to the vehicle based on a time of flight of communications between the mobile communication unit and three or more transceivers positioned in the vehicle.
 11. The communication system of claim 10, wherein the base station is configured to determine the location of the mobile communication unit relative to the vehicle based on a time of flight of an ultra-wide band communication between the mobile communication unit and the three or more transceivers positioned in the vehicle.
 12. The communication system of claim 1, wherein the limited-response mode comprises the mobile communication unit operating in accordance with a limited-response duty cycle.
 13. A method of facilitating control over a function of a vehicle, the method comprising: providing a base station and a mobile communication unit, the base station comprising a first transmitter and a first receiver; detecting a movement of the mobile communication unit and outputting a signal indicative of the movement via a motion sensor; transmitting the signal from the first transmitter to the mobile communication unit; receiving the signal from the mobile communication unit; and determining a location of the mobile communication unit relative to the vehicle, wherein, when the location of the mobile communication unit relative to the vehicle remains substantially unchanged for a predetermined period of time, causing the mobile communication unit to operate in accordance with a limited-response mode.
 14. The method of claim 13, wherein said causing the mobile communication unit to operate in accordance with the limited-response mode is performed when at least one of: (i) the location of the mobile communication unit relative to the vehicle remains within an authorization zone for a predetermined period of time; (ii) the location of the mobile communication unit relative to the vehicle is within an authorization zone and remains relatively unchanged for a predetermined period of time; and (iii) the location of the mobile communication unit relative to the vehicle is within an authorization zone and the vehicle remains free from interruption for a predetermined period of time.
 15. The method of claim 13, further comprising: receiving the signal indicative of the movement of the mobile communication unit; wherein said causing the mobile communication unit to operate in accordance with a limited-response mode is performed when the signal is indicative of said movement satisfying a predetermined limited-response criteria.
 16. The method of claim 13, further comprising: receiving the signal indicative of the movement of the mobile communication unit; and when the signal is indicative of said movement satisfying a predetermined high-response criteria, causing the mobile communication unit to resume operating in accordance with a high-response duty cycle.
 17. The method of claim 13, wherein said determining a location of the mobile communication unit relative to the vehicle is performed based on a time of flight of communications between the mobile communication unit and three or more transceivers positioned in the vehicle.
 18. The method of claim 13, wherein the limited-response mode comprises causing the mobile communication unit to operate in accordance with a limited-response duty cycle.
 19. A vehicle comprising the communication system of claim
 1. 